Observer-based adaptive threshold diagnosis method for open-switch faults of voltage source inverters
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ORIGINAL ARTICLE
Observer‑based adaptive threshold diagnosis method for open‑switch faults of voltage source inverters Haoran Yin1,2 · Yong Chen1,2 · Zhangyong Chen1,2 Received: 5 December 2019 / Revised: 20 July 2020 / Accepted: 28 July 2020 © The Korean Institute of Power Electronics 2020
Abstract In this paper, the problem of open-switch faults of a voltage source inverter system is investigated. A new fault diagnosis method based on an observer and an adaptive threshold is proposed. This method only needs to utilize the signals existing in a system without the need for extra hardware circuits. First, an observer is designed on a model of a three-phase voltage source inverter system to estimate currents. Then, an adaptive threshold is designed on fault residuals, dynamics of the currents and variations of the system operating state. Moreover, the dead time and switching delay time are also included in the threshold to consider practical applications. Furthermore, to achieve on-line real-time diagnosis and to improve the reliability of the proposed method, the averages of the current residuals in a current fundamental period are defined as diagnostic variables. Finally, the reliability and effectiveness of the proposed method are verified by simulation and experiment results. Keywords Voltage source inverter · Open-switch fault · Fault diagnosis · Observer · Adaptive threshold
1 Introduction During the past few decades, voltage-source inverters (VSIs) have attracted a great deal of attention because of their benefits such as low cost, high output quality, high efficiency, etc.[1, 2]. Therefore, they have been extensively studied and applied in various fields in the last several years, e.g. smartgrids [3], new energy systems [4] and so on. However, inverters are very sensitive and susceptible under working condition due to the high-frequency switching of power switches, which can result in a series of unpredictable losses. According to the authors of [5], about 80% of the failures in converter systems are from the power semiconductor devices. Thus, accurate and fast fault diagnosis is important when it comes to improving the reliability of a VSI system [6]. The faults in VSI systems can be mainly divided into two categories: open-circuit faults [7] and short-circuit faults * Yong Chen [email protected] 1
School of Automation Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu, China
Institute of Electric Vehicle Driving System and Safety Technology, UESTC, Chengdu, China
2
[8]. After a short-circuit fault occurs, its detection, location, and isolation often need to be achieved in a short period of time [6]. In practical engineering, the system is usually protected by specific hardware circuits, or the short-circuit fault is converted into an open-circuit fault by fast fuses. An open-circuit fault is different from a short-circuit fault in that it has a slower reaction time. Thus, diagnostic methods need to be proposed to detect and locate faults, which is helpf
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